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TELEPHONIG APPARATUS.

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UNITED STATES PATENT OFFICE.

CHARLES MILDE, OF PARIS, FRANCE.

TELEPHONIC APPARATUS.

SPECIFICATION forming part of Letters Patent No. 518,263, dated April17,1894- Application filed October 31, 1393. Serial No. 489,641- (Nomodel.)

To all whom it may concern:

Be it known that I, CHARLES MILDE, a citizen of the Republic of France,and a resident of Paris, Department of the Seine, France, have inventedcertain new and useful Improvements in Telephonic Apparatus, of whichthe following is a specification.

My invention relates to atelephonc which, besides being very simple inits construction has the advantage that it can be used at the same timeas a short and long distance tele-' phone by reason of the extremesensitiveness of the transmitter as well as the receiver.

In the drawings, Figure 1, showsthe complete telephone consisting of themicrophone and of the receiver. Fig. 2, is a sectional view of themicrophone on an enlarged scale.

The same letters refer always to the same parts.

The following is the description of the microphone Fig. 2. Aisa part ofthe vibrating plate of the telephone to which the microphone is fixed bythe means of a screw B which itself isfixed to a metallic socket C. Asecond screw serves for fastening there, one of the wires of the circuittosaid socket. A Washer of cork D is placed between the bottom of thesocket and the vibrating plate in order to deaden the joint. Themicrophone itself is fixed so that it can move in said socket C. Itconsists of two circular plates E of thin metal and with a corrugatedsurface which, when placed the one upon the other forms a flat box aboutfive-sixths of which is filled with sieved granules of coke or carbon,chemically purified. Two sticks or beads of carbon F are arrangedthrough the center of the platesE and are insulated from contact withthe metal through the means of a paper-strip G. The two heads are incontact with said semi-conducting material in the box. In order toincrease the sensitiveness of the instrument both beads are hollowed atthe bottom and the hollow spaces are filled with lead, H. A small lowersocket I corresponds to the upper socket C of the plate A and isprovided with a small screw for the other wire of the circuit.

After having thus given a detailed description of a practicalconstruction of my improved microphone I wish it understood that myinvention is not limited to that construction alone. The lead placed inthe hollow of the two carbon sticks are simply weights united to one ofthe carbons or to both if necessary. I can make the weights of otherheavy material; I can give them the shape of rings encircling thecarbons, in the shape of washers located at the bottom of the sockets Cand I. I can simply make the sockets themselves heavier; in short,changes in the shape or in the material which do not affect theprinciple itself of the invention which is plainly'and preciselycharacterized by the union of suitable weights to one or to both carbonbeads of my microphone.

Instead of fixing the microphone to the vibrating plate by means of ascrew I can glue the same togetherwith some appropriate glue.

The insulating fittings can be of any propermaterial. The conductingwires instead of being fixed by screws can be knotted around the beads,they can be pressed between the sockets and the carbons, in short theycan be fastened in any suitable way.

I claim as my invention- 1. A microphone consisting ofa metalliccorrugated box partly filled with granulated and purified coke, said boxhaving a carbon stud or head extending through it at each side andcarrying a weight, one of the beads being connected to the vibratingtransmission plate, substantially as described.

2. A microphone comprising the flat box made up of the corrugatedplates, the vibrating, diaphragm, the opposing carbon studs extendingthrough the corrugated plates and centrally thereof, the circuitconnections and granulated filling in the box, said box extendinglaterally around the opposing studs, substantially as described.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two witnesses.

CHARLES MILDE. Witnesses: M. CORROYER,

CLYDE SHROPSHIRE.

